An eyelet terminal is essentially a flat ring of electrically conductive metal for receiving a bolt or a similar connector, and a radially extending portion for connection to the end of a length of wire by crimping or soldering. Eyelet terminals are used in many types of electrical systems, including those of automotive vehicles, to connect wires to electrical ground or to other electrical system components. In a typical automotive grounding connection, the eyelet terminal is bolted to a piece of sheet metal such as a vehicle body panel. Sometimes a lock washer is inserted between the bolt head and the terminal ring to make the bolted connection more secure against vibration.
In such automotive grounding applications, the eyelet terminal and its attached wire, the bolt, and the lock washer are typically shipped to the vehicle final assembly plant as separate components, then assembled with one another immediately prior to being bolted to the body panel. This assembly technique is more time consuming, more expensive, and more prone to human error than if the parts were shipped and assembled to the vehicle as a unit.
Some eyelet terminals include projections or serrations on the lower surface of the ring for cutting into the sheet metal slightly when the terminal is bolted tightly against the body panel, and thus ensuring better electrical contact than is provided by mere planar contact between the terminal and the metal. The scratches formed in the metal by the serrations, though, promote the formation of corrosion.